Charge-Density-Wave Formation in the Doped Two-Leg Extended Hubbard Ladder (Condensed Matter : Electronic Structure, Electrical, Magnetic and Optical Properties)

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We investigate the electronic properties of a doped two-leg Hubbard ladder with both the onsite and nearest-neighbor Coulomb repulsions by using the weak-coupling renormalization-group method. It is shown that, for strong nearest-neighbor repulsions, the charge-density-wave state coexisting with the p-density-wave state becomes a dominant fluctuation where spins form intrachain singlets. By increasing doping rate, we have also shown that the effects of the nearest-neighbor repulsions are reduced and the system exhibits a quantum phase transition into the d-wave-like (or rung-singlet) superconducting state. We derive the effective fermion theory which describes the critical properties of the transition point with the gapless excitation of magnon. The phase diagram of the two-leg ladder compound, Sr_<14-x>Ca_x-Cu_<24>O_<41>, is discussed.
社団法人日本物理学会の論文
2004-04-15